The present invention is directed generally to chemical feeders. In particular, the present invention is directed to automatic chemical feeders useful for preparing a liquid solution of a chemical material, e.g., a sanitizing chemical, and dispensing such solution at or to a location, e.g., a large body of water, where it is to be used. More particularly, the present invention is directed to a chemical feeder that automatically dispenses controlled amounts of an aqueous solution of calcium hypochlorite in a reliable, efficient and cost effective manner for treatment of water systems, e.g., water treatment plants, potable water supplies, water for industrial or process usage, waste water systems, water systems for cooling towers, run-off water, swimming pools, hot tubs and the like.
Chemical feeders for producing aqueous solutions of water treating agents are well known and have been utilized with processes for the disinfection of effluent from sewage treatment plants, for the chlorination of water in swimming pools and hot tubs, and for the delivery of other water soluble chemicals to aqueous streams and water systems. Chemical feeders designed for the disinfection of effluent from sewage treatment plants have been designed to overcome the drawbacks of previous chlorine treatment systems, which required extensive daily attention by operators in order to achieve acceptable disinfection of the sewage plant effluent. Chlorine and other sanitizing chemicals are used in swimming pool and hot tub applications to control the growth of algae and other organisms in the water. The concentration of the sanitizing chemical in a body of water, e.g., a swimming pool, must be kept between the concentration level that is effective to eliminate algae and other objectionable organisms and below the concentration level that is harmful to the user. Consequently, chemical feeders used in treating bodies of water, e.g., swimming pools and hot tubs, have been designed to alleviate the shortcomings, e.g., wide variations in treating agent concentration, that typically accompany manual treatment, e.g., manual chlorination and manual chemical addition. Examples of existing chemical feeders for treating aqueous streams and/or bodies of water, e.g., sewage effluent, pools and hot tubs, can be found in U.S. Pat. Nos. 3,595,786; 3,595,395; 4,584,106; 4,732,689; and 4,759,907.
One difficulty associated with some of these prior art designs is that they can result in the build up of pressurized air within the chemical feeder, which may lead to potentially dangerous conditions in the event the chemical feeder ruptures or is inadvertently opened while pressurized. An additional disadvantage of some of the prior art chemical feeders is a build up of chemical residue within portions of the chemical feeder. A build up of chemical residue can detrimentally affect the chemical delivery rate of the feeder, eventually requiring it to be taken off-line and cleaned. These difficulties may significantly increase the amount of maintenance required for operation of a chemical feeder.
It would be desirable to develop a new and useful chemical feeder that overcomes the aforementioned drawbacks of the prior art while maintaining a substantially constant delivery rate of chemical treating agent. It would also be particularly desirable that such a new chemical feeder be easy to use, e.g., easy to recharge with chemical treating agent, and safe to operate, in particular, with regard to minimizing substantially the build up of pressurized air therein.
In accordance with the present invention, there is provided a chemical feeder comprising:
(a) a housing having a chamber therein;
(b) at least one canister for holding solid chemical material supported within said chamber, said canister having a plurality of perforations in its lower portion,
(c) at least one inlet in said housing extending into said chamber for introducing a liquid into said chamber in proximity to said perforations in said canister to contact said solid chemical material with said introduced liquid, said perforations in said canister being such as to expose only the lower portions of said solid chemical material contained within said canister to the flow of liquid introduced through said inlet, and
(d) at least one outlet in said housing through which liquid having chemical material dissolved therein is withdrawn from said chamber, said outlet being adapted to maintain said chamber substantially flooded with liquid during operation.
In another embodiment of the present invention, the inlet for supplying liquid to the chamber of the housing is located in a sidewall of the housing and provides a tangential, cyclonic flow of liquid within the chamber.
In a further embodiment of the present invention the outlet of the chemical feeder includes an overflow standpipe positioned along a longitudinal centerline of the housing, which maintains the chamber substantially flooded with liquid during operation of the feeder.
The features that characterize the present invention are pointed out with particularity in the claims which are annexed to and form a part of this disclosure. These and other features of the invention, its operating advantages and the specific objects obtained by its use will be more fully understood from the following detailed description and the accompanying drawings in which preferred embodiments of the invention are illustrated and described, and in which like reference characters designate corresponding parts.
Other than in the operating examples, or where otherwise indicated, all numbers and values, such as those expressing quantities of ingredients and reaction conditions, used in the specification and claims are to be understood as modified in all instances by the term xe2x80x9cabout.xe2x80x9d